The sperm acrosome functions during the fertilization process by releasing its contents of hydrolytic enzymes, thus facilitating sperm penetration through their investments which surround the ovum. The process by which the enzymes are released is the result of the gradual yet complete breakdown of the plasma membranes, specificially covering the acrosome, and the outer acrosomal membrane. This process has been termed the "acrosome reaction" and occurs universally in mammalian sperm. Ovarian follicular fluid, considered part of the ovulated cell mass, has been examined shown to induce functional acrosome reaction in several mammalian species. The work of this proposed project is to investigate the acrosome reaction induced in vitro by follicular fluid from an ultrastructural, histological, functional bases. And to further characterize the nature of the component(s) within the follicular fluid which is capable of inducing the acrosome reaction, to purify the component(s) and to study its chemical nature and physical characteristics. BIBLIOGRAPHIC REFERENCES: Ultrastructural Observations of the Time Sequence of the Acrosome Reaction. C.A. Singhas and G. Oliphant. Fed. Proced. 35, 727 (1976). Sperm decapacitation by Membrane Stabilization. L. Eng and G. Oliphant. Fed. Proced. 35, 727 (1976).